Furthermore, few data, all on inflammatory bowel diseases, are reported on the possible association between the insufficiency of vitamin D and biological disease-modifying anti-rheumatic drugs (b-DMARDs) response, with the majority of evidence in favor of poor response to anti-tumor necrosis factor-alpha (anti TNF-α) in patients with vitamin D insufficiency [25,26,27]. This evidence concerns the gene TNF and inflammatory bowel disease.